LST CPU Speedups by GNiendorf · Pull Request #245 · SegmentLinking/cmssw

GNiendorf · 2026-03-18T16:43:40Z

This PR Timing (CPU) - commit 2 (pre-checks, exact trig simplifications, and additional early exits)

This PR Timing (CPU) - commit 1 (reducing redundant memory loads)

Master Timing (CPU)

GNiendorf · 2026-03-18T17:31:20Z

run-ci: all

github-actions · 2026-03-18T17:58:10Z

The PR was built and ran successfully in standalone mode running on CPU. Here are some of the comparison plots.

The full set of validation and comparison plots can be found here.

Here is a timing comparison:

   Evt    Hits       MD       LS      T3       T5       pLS       pT5      pT3      TC       Reset    Event     Short             Rate
   avg     29.0    323.1    245.5    138.1     48.6    695.7     10.9    116.6    119.7    208.9      0.1    1936.1    1211.5+/- 290.1     602.5   explicit[s=4] (target branch)
   avg     28.1    218.8    178.6    127.2     49.7    700.7     10.6    109.5     83.0    202.6      0.1    1708.9     980.1+/- 239.1     545.5   explicit[s=4] (this PR)

github-actions · 2026-03-18T19:22:27Z

The PR was built and ran successfully with CMSSW running on CPU. Here are some plots.

OOTB All Tracks

The full set of validation and comparison plots can be found here.

GNiendorf · 2026-03-19T10:57:53Z

run-ci: all
modifiers: gpu

github-actions · 2026-03-19T11:19:17Z

The PR was built and ran successfully in standalone mode running on GPU. Here are some of the comparison plots.

The full set of validation and comparison plots can be found here.

Here is a timing comparison:

   Evt    Hits       MD       LS      T3       T5       pLS       pT5      pT3      TC       Reset    Event     Short             Rate
   avg     31.1      0.2      0.4      0.6      0.9      0.3      0.6      0.5      0.3      1.4      0.0      36.2       4.8+/-  2.7      36.2   explicit[s=1]
   avg      1.1      0.3      0.5      0.8      1.0      0.3      0.8      0.7      0.4      1.8      0.0       7.7       6.3+/-  2.8       4.0   explicit[s=2]
   avg      2.0      0.6      0.8      1.2      1.5      0.4      1.2      1.0      0.6      2.8      0.0      12.1       9.7+/-  3.5       3.2   explicit[s=4]
   avg      3.2      0.9      1.2      1.7      2.0      0.5      1.7      1.3      0.8      3.9      0.0      17.2      13.5+/-  4.3       3.0   explicit[s=6]
   avg      3.7      1.3      1.7      2.4      2.6      0.7      2.3      1.6      1.0      4.9      0.0      22.3      17.9+/-  4.6       2.9   explicit[s=8] (target branch)
   avg     31.1      0.2      0.4      0.6      0.9      0.3      0.6      0.5      0.3      1.4      0.0      36.2       4.8+/-  2.6      36.3   explicit[s=1]
   avg      1.3      0.3      0.5      0.7      1.0      0.3      0.8      0.7      0.4      1.8      0.0       7.9       6.4+/-  2.8       4.1   explicit[s=2]
   avg      2.2      0.6      0.8      1.2      1.5      0.4      1.2      1.0      0.6      2.8      0.0      12.2       9.6+/-  3.3       3.2   explicit[s=4]
   avg      3.0      0.9      1.2      1.7      2.1      0.5      1.7      1.3      0.8      3.8      0.0      17.0      13.5+/-  4.1       3.0   explicit[s=6]
   avg      3.6      1.3      1.7      2.3      2.6      0.7      2.2      1.7      1.0      5.0      0.0      22.2      18.0+/-  4.5       2.9   explicit[s=8] (this PR)

GNiendorf · 2026-03-19T11:22:05Z

@slava77 I think this PR is good to go. Represents most of the boiler-plate changes of the CPU speedups PR.

github-actions · 2026-03-19T12:35:39Z

The PR was built and ran successfully with CMSSW running on GPU. Here are some plots.

OOTB All Tracks

The full set of validation and comparison plots can be found here.

slava77 · 2026-03-19T13:29:14Z

the GPU variant should have one more significant digit in the component columns (the total can be still with .1.
I don't have a particluar preference for this PR or separate.

slava77

nice updates.
I think the comment cleanup in the MiniDoublet code is a bit too aggressive. While some removals may be clean for some tautological docs, quite a bit is going to lose clarity. Please recover

RecoTracker/LSTCore/src/alpaka/MiniDoublet.h

RecoTracker/LSTCore/src/alpaka/PixelTriplet.h

RecoTracker/LSTCore/src/alpaka/Segment.h

RecoTracker/LSTCore/src/alpaka/Triplet.h

GNiendorf · 2026-03-19T20:52:44Z

run-ci: all

GNiendorf · 2026-03-19T21:02:54Z

run-ci: all

GNiendorf · 2026-03-19T21:16:17Z

run-ci: all
modifiers: gpu

github-actions · 2026-03-19T21:23:16Z

The PR was built and ran successfully in standalone mode running on CPU. Here are some of the comparison plots.

The full set of validation and comparison plots can be found here.

Here is a timing comparison:

   Evt    Hits       MD       LS      T3       T5       pLS       pT5      pT3      TC       Reset    Event     Short             Rate
   avg     28.2    324.2    243.0    136.6     47.8    698.4     10.9    114.7    118.8    208.7      0.1    1931.4    1204.8+/- 289.9     596.7   explicit[s=4] (target branch)
   avg     31.1    219.2    182.6    133.5     47.6    698.9     10.8    110.7     83.1    185.9      0.1    1703.5     973.4+/- 227.2     541.9   explicit[s=4] (this PR)

github-actions · 2026-03-19T22:18:47Z

The PR was built and ran successfully with CMSSW running on GPU. Here are some plots.

OOTB All Tracks

The full set of validation and comparison plots can be found here.

github-actions · 2026-03-19T22:23:37Z

The PR was built and ran successfully with CMSSW running on CPU. Here are some plots.

OOTB All Tracks

The full set of validation and comparison plots can be found here.

github-actions · 2026-03-19T22:39:10Z

The PR was built and ran successfully in standalone mode running on GPU. Here are some of the comparison plots.

The full set of validation and comparison plots can be found here.

Here is a timing comparison:

   Evt    Hits       MD       LS      T3       T5       pLS       pT5      pT3      TC       Reset    Event     Short             Rate
   avg     32.5      0.2      0.4      0.6      0.9      0.3      0.6      0.5      0.3      1.4      0.0      37.6       4.8+/-  2.6      37.6   explicit[s=1]
   avg      1.1      0.4      0.5      0.8      1.0      0.3      0.8      0.7      0.4      1.8      0.0       7.8       6.4+/-  2.9       4.0   explicit[s=2]
   avg      1.8      0.6      0.8      1.1      1.5      0.4      1.2      1.0      0.6      2.8      0.0      11.9       9.7+/-  3.5       3.1   explicit[s=4]
   avg      2.6      0.9      1.3      1.7      2.0      0.5      1.7      1.2      0.8      3.9      0.0      16.6      13.5+/-  4.1       2.9   explicit[s=6]
   avg      3.4      1.3      1.7      2.3      2.6      0.7      2.3      1.6      1.0      5.0      0.0      21.9      17.8+/-  4.5       2.8   explicit[s=8] (target branch)
   avg     32.6      0.2      0.4      0.6      0.8      0.3      0.6      0.5      0.3      1.4      0.0      37.7       4.8+/-  2.5      37.7   explicit[s=1]
   avg      1.2      0.4      0.5      0.8      1.0      0.3      0.8      0.8      0.4      1.9      0.0       7.9       6.5+/-  2.8       4.1   explicit[s=2]
   avg      1.8      0.6      0.8      1.1      1.5      0.4      1.2      1.0      0.6      2.8      0.0      11.8       9.6+/-  3.5       3.1   explicit[s=4]
   avg      2.6      1.0      1.2      1.7      2.0      0.5      1.7      1.3      0.8      4.0      0.0      16.7      13.6+/-  4.0       2.9   explicit[s=6]
   avg      3.4      1.3      1.7      2.2      2.6      0.7      2.2      1.7      1.0      5.0      0.0      21.9      17.8+/-  4.5       2.8   explicit[s=8] (this PR)

GNiendorf · 2026-03-19T23:04:47Z

run-ci: all

github-actions · 2026-03-19T23:24:47Z

The PR was built and ran successfully in standalone mode running on CPU. Here are some of the comparison plots.

The full set of validation and comparison plots can be found here.

Here is a timing comparison:

   Evt    Hits       MD       LS      T3       T5       pLS       pT5      pT3      TC       Reset    Event     Short             Rate
   avg     27.7    322.4    240.8    132.7     45.6    696.8     10.6    114.4    115.1    208.0      0.2    1914.4    1189.9+/- 285.9     594.9   explicit[s=4] (target branch)
   avg     30.6    102.9    179.8    126.4     48.6    681.7     10.6     39.0     67.1    209.9      0.1    1496.7     784.5+/- 195.0     491.4   explicit[s=4] (this PR)

github-actions · 2026-03-20T00:19:08Z

The PR was built and ran successfully with CMSSW running on CPU. Here are some plots.

OOTB All Tracks

The full set of validation and comparison plots can be found here.

GNiendorf · 2026-03-20T01:22:10Z

run-ci: all

GNiendorf · 2026-03-20T01:22:23Z

run-ci: all
modifiers: gpu

github-actions · 2026-03-20T01:41:41Z

The PR was built and ran successfully in standalone mode running on CPU. Here are some of the comparison plots.

The full set of validation and comparison plots can be found here.

Here is a timing comparison:

   Evt    Hits       MD       LS      T3       T5       pLS       pT5      pT3      TC       Reset    Event     Short             Rate
   avg     27.8    323.7    246.6    133.8     45.9    694.1     10.6    113.1    116.7    208.9      0.8    1922.1    1200.1+/- 288.6     593.4   explicit[s=4] (target branch)
   avg     28.9    104.0    137.1    117.7     50.5    685.8     10.4     38.1     68.6    188.3      0.1    1429.6     715.0+/- 182.9     472.5   explicit[s=4] (this PR)

github-actions · 2026-03-20T01:41:50Z

The PR was built and ran successfully in standalone mode running on GPU. Here are some of the comparison plots.

The full set of validation and comparison plots can be found here.

Here is a timing comparison:

   Evt    Hits       MD       LS      T3       T5       pLS       pT5      pT3      TC       Reset    Event     Short             Rate
   avg     31.7      0.2      0.4      0.5      0.8      0.3      0.6      0.4      0.3      1.3      0.0      36.6       4.7+/-  2.4      36.6   explicit[s=1]
   avg      1.1      0.3      0.5      0.7      1.0      0.3      0.8      0.5      0.4      1.8      0.0       7.5       6.2+/-  2.9       3.9   explicit[s=2]
   avg      1.9      0.5      0.9      1.1      1.5      0.4      1.2      0.8      0.6      2.9      0.0      11.7       9.5+/-  3.5       3.0   explicit[s=4]
   avg      2.6      0.9      1.3      1.6      2.1      0.5      1.8      1.0      0.9      3.9      0.0      16.6      13.5+/-  4.0       2.9   explicit[s=6]
   avg      3.3      1.4      1.8      2.3      2.6      0.6      2.3      1.3      1.1      5.0      0.0      21.8      17.8+/-  4.6       2.8   explicit[s=8] (target branch)
   avg     32.2      0.2      0.4      0.5      0.8      0.3      0.6      0.4      0.3      1.3      0.0      37.2       4.7+/-  2.5      37.2   explicit[s=1]
   avg      1.0      0.3      0.5      0.7      1.0      0.3      0.8      0.5      0.4      1.8      0.0       7.4       6.1+/-  2.8       3.8   explicit[s=2]
   avg      1.8      0.6      0.9      1.1      1.5      0.4      1.2      0.8      0.6      2.9      0.0      11.7       9.4+/-  3.7       3.0   explicit[s=4]
   avg      2.6      0.9      1.3      1.6      2.0      0.5      1.7      1.0      0.8      3.9      0.0      16.5      13.4+/-  3.9       2.9   explicit[s=6]
   avg      3.3      1.4      1.7      2.4      2.7      0.7      2.4      1.3      1.1      5.0      0.0      22.1      18.1+/-  4.2       2.8   explicit[s=8] (this PR)

github-actions · 2026-03-20T02:37:36Z

The PR was built and ran successfully with CMSSW running on GPU. Here are some plots.

OOTB All Tracks

The full set of validation and comparison plots can be found here.

github-actions · 2026-03-20T02:49:31Z

The PR was built and ran successfully with CMSSW running on CPU. Here are some plots.

OOTB All Tracks

The full set of validation and comparison plots can be found here.

GNiendorf force-pushed the cpu_speedups_hoist branch from f5fbe61 to 83f2297 Compare March 18, 2026 17:30

GNiendorf marked this pull request as ready for review March 18, 2026 17:37

slava77 reviewed Mar 19, 2026

View reviewed changes

GNiendorf force-pushed the cpu_speedups_hoist branch 2 times, most recently from 9aad224 to 727bac8 Compare March 19, 2026 20:50

remove redundant memory loads

2375562

GNiendorf force-pushed the cpu_speedups_hoist branch from 727bac8 to 2375562 Compare March 19, 2026 20:59

GNiendorf force-pushed the cpu_speedups_hoist branch from a2305fb to df0990a Compare March 19, 2026 23:24

GNiendorf changed the title ~~Remove Redundant Memory Loads~~ CPU Optimizations Mar 19, 2026

GNiendorf changed the title ~~CPU Optimizations~~ LST CPU Speedups Mar 19, 2026

pre-checks, exact trig simplifications, and additional early exits

6ba26d8

GNiendorf force-pushed the cpu_speedups_hoist branch from df0990a to 6ba26d8 Compare March 20, 2026 01:17

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GNiendorf commented Mar 18, 2026 •

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